Who is Participating?

An Intranet usually consists of custom pages / modules specific to that companies individuals needs. My first job out of college was for a really small software company and one of the many hats I wore was to create and maintain the company intranet. A lot of it was inventory forms, and other custom applications. Had I chosen SP, it probably would have been overkill, as the setup and learning curve of SP would have taken more time than just doing the dev work myself.

with that said, i've worked at companies that utilized SP for their Intranets, and it was great. SP is really good at content management, ie: file document libraries, collections of different types of data, etc and it was easy to use and implement once you got over the basic learning curve.

Figure out what your requirements are, do you just need to serve static pages? or do you need to manage a lot of data? once you narrow down what you're looking to do, then you can start to figure out what platform is best for you.

that is a rather broad question. The question title suggests that intranet design and SharePoint are not compatible (your use of "vs"). That is not so. In fact, these days the majority of corporate intranets are based on the SharePoint platform.

There is the product- and vendor- agnostic Intranets conference in Australia. Almost every session that deals with the underlying software is about SharePoint. And that has been running for a few years.

So, it's definitely not "intranet design versus SharePoint".

The best way to pin down the requirements is to ask your users (who consume the content) and your stakeholders (who provide the content). What do each of these require from an intranet? You need to do a careful analysis of both groups' expectations and then find the golden middle ground.

Most folks who publish their content to an intranet feel that everybody wants to know it. Most folks who read that published content feel that they are not really interested in that.
This is the analysis you need to do.

We don't know your business, your users, your topics. There is not easy formula to help you figure out what your intranet should look like. You'll have to ask your users and do the hard work yourself.